Phase shifting mask for equal line/space dense line patterns

Abstract

A phase shifting mask suited for equal line/space, small pitched, dense line pattern is disclosed. The phase shifting mask includes a transparent substrate, a partially shielded mesa line pattern of first phase formed on the substrate, and a transparent recessed line pattern of second phase etched into the substrate and is disposed right next to the partially shielded mesa line pattern. The partially shielded mesa line pattern has a plurality of alternating opaque regions and transparent regions of the first phase. The partially shielded mesa line pattern and the clear recessed line pattern have the same line width. The light that passes through the transparent regions of the first phase and the light that passes through the transparent recessed line pattern of second phase have a phase difference of 180 degree.

1 . A phase-shifting mask (PSM), comprising: 
 a transparent substrate;    columns of first phase-shifting line patterns having a first substrate thickness of first phase disposed on the transparent substrate along a first direction, wherein each of the first phase-shifting line patterns is alternately disposed thereon with 100% clear regions of the first phase and light blocking areas that forbid light transmission; and    columns of 100% light transmittable second phase-shifting line patterns, in parallel with the first phase-shifting line patterns, having a second substrate thickness of second phase, wherein the first phase-shifting line patterns and second phase-shifting line patterns are alternately disposed on the transparent substrate.    
     
     
         2 . The PSM of  claim 1  wherein the first phase-shifting line patterns and second phase-shifting line patterns have substantially the same line width.  
     
     
         3 . The PSM of  claim 1  wherein the light blocking areas are equal in size.  
     
     
         4 . The PSM of  claim 1  wherein the light blocking areas are disposed equally spaced apart along each of the first phase-shifting line patterns.  
     
     
         5 . The PSM of  claim 1  wherein the light blocking areas on odd columns of the first phase-shifting line patterns are aligned with a second direction normal to the first direction, while the light blocking areas on even columns of the first phase-shifting line patterns are aligned with the second direction.  
     
     
         6 . The PSM of  claim 1  wherein each of the light blocking areas has a length along the first direction ranging from λ/4 to 3λ/4 (λ: wavelength of exposure light source of a stepper and scanner).  
     
     
         7 . The PSM of  claim 1  wherein each of the 100% clear regions has a length along the first direction ranging from λ/4 to 3λ/4 (λ: wavelength of exposure light source of a stepper and scanner).  
     
     
         8 . The PSM of  claim 1  wherein the first substrate thickness is greater than the second substrate thickness such that light that passes through the 100% clear regions of the first phase and light that passes through the 100% light transmittable second phase-shifting line patterns of second phase have a phase difference of 180 degree.  
     
     
         9 . The PSM of  claim 1  wherein the transparent substrate is a quartz substrate.  
     
     
         10 . The PSM of  claim 1  wherein a constant distance is defined between two adjacent said light blocking areas along each of the first phase-shifting line patterns.  
     
     
         11 . A phase-shifting mask (PSM), comprising: 
 a transparent substrate;    a first phase-shifting mesa line pattern having a first substrate thickness of first phase disposed on the transparent substrate, wherein the first phase-shifting mesa line pattern has thereon a clear region of the first phase that is disposed between adjacent light blocking areas; and    a second phase-shifting recessed line pattern, being in parallel with the first phase-shifting mesa line patterns, having a second substrate thickness of second phase etched into the transparent substrate.    
     
     
         12 . The PSM of  claim 11  wherein the first phase-shifting mesa line pattern and second phase-shifting recessed line pattern have substantially the same line width.  
     
     
         13 . The PSM of  claim 11  wherein the light blocking areas are equal in size.  
     
     
         14 . The PSM of  claim 11  wherein the light blocking areas are disposed equally spaced apart along each of the first phase-shifting mesa line patterns.  
     
     
         15 . The PSM of  claim 11  wherein each of the light blocking areas has a length along the first direction ranging from λ/4 to 3λ/4 (λ: wavelength of exposure light source of a stepper and scanner).  
     
     
         16 . The PSM of  claim 11  wherein the clear region has a length along the first direction ranging from λ/4 to 3λ/4 (λ: wavelength of exposure light source of a stepper and scanner).  
     
     
         17 . The PSM of  claim 11  wherein the first substrate thickness is greater than the second substrate thickness such that light that passes through the clear region of the first phase and light that passes through the second phase-shifting recessed line patterns of the second phase have a phase difference of 180 degree.  
     
     
         18 . The PSM of  claim 11  wherein the transparent substrate is a quartz substrate.  
     
     
         19 . The PSM of  claim 11  wherein the light blocking areas are made from chrome.